On my way back from a weekend trip i had three blow outs! Used my spare my friends spare then had to go to Walmart. my trailer is an 05 Boatmate and they the original tires and figure the tires were dry rotted. Bearings did not get hot but I have never really done much maintenence. What maintenance do I need to do and how often? What kind of tires should I get and can I put 15 in wheels on trailer (have a set i took off a jeep that are black)

when you store your boat for long periods of time you are supposed to move the trailer around every once in a while or put the trailer on blocks to ease the pressure on a single spot on the tires and the axles..... is that possibly part of the problem? As for your second question an 05 Boatmate should have oil bath hubs that are maintence free, but not possitive and I would still keep an eye on them

Tires are affected by heat, UV light, and age. The heat and the UV light age them faster. The rubber loses it's volitiles. Those are the petroleum products that can evaporate over time. You can recondition that but those compounds are expensive to add so it's better to protect them. Cover or shade the tires so they don't get direct sunlight. Use 303 or some other protectant on the rubber to help them handle the light. Just make sure it gives UV protection. Tow the trailer around instead of letting it just sit there. The tire will last longer if it is used than if it is stationary for long periods.

Check your trailer brakes and look at the trialer tires for cupping or feathering which might indicate alignment issues on the trailer. And check or replace the valve stems as lakeski suggested.

The oil bathed hubs still need servicing. UPF is the company that manufacture the axles and hubs that BoatMate uses. They recommend changing the oil in the bearings every two years or 20,000 miles. Also they recommend using Royal Purple synthetic oil in 50 wt.

As far as changing the wheel and tire size is up to you. My BoatMate trailer has 205/75/R14 from the factory. You can now get custom wheels and low profile tires up to 18in. I've heard some people putting 20in wheels on their trailers. I personally like the looks of the low profile tires and wheels.

UFP sent you a new lubricant they had specifically formulated. It becomes more fluid at hub operating temperature and less fluid when cooled which cuts down on annoying trickles of oil from the back seal.

The tires blowing could be due to a number of issues, many which were listed above. However, the number one culprit is low tire pressure. Keep the tires at the max cold inflation shown on the sidewall.